Germicidal soaps



Patented Nov. 8, 1966 3,284,363 GERMICIDAL SOAPS Willard M. Bright, Winston-Salem, N.C., assignor to Lever Brothers Company, New York, N.Y., a corporation of Maine No Drawing. Continuation of application Ser. No. 3%,751, June 27, 1960. This application July 12, 1965, Ser. No. 471,475

4 Claims. (Cl. 252107) This application is a continuation of my copending application Serial No. 38,751, filed June 27, 1960, and now abandoned.

The present invention relates to soap compositions, and more particularly to germicidal soap bars.

Soap bars are effective in their cleansing properties, but they have no germicidal activity so that they are ineffective in killing skin bacteria. When small amounts of 3,4,S-tribromosalicylanilide are incorporated into soap bars, there are produced bars having high germicidal activity. Such bars, however, are cream colored rather than pure white. While this discoloration of the soap bars may be accepted by some consumers, it is objectionable to many consumers who want to purchase white soap bars which have germicidal properties. On the other hand, when 3,4,4'-trichlorocarbanilide at low levels is incorporated into soap bars, the resulting bars have only very slight germicidal activity.

I have found that germicidal soap bars can be produced having a satisfactorily high germicidal activity even though they contain little of 3,4,5-tribromosalicylanilide, provided the bars contain both 3,4,5-tribromosalicylanilide and 3,4,4-trichlorocarbanilide. I have .further found quite unexpectedly that this mixture of germicides has synergistic germicidal activity in soap bars but not in non-soap bars. That is to say soap bars containing both 3,4,S-tribromosalicylanilide and 3,4,4-trichlorocarbanilide have a germicidal activity which is higher than the sum of the activities of soap bars containing either of these germicides alone in the same amount as present in soap bars containing both of these germicides. This synergistic effect has been observed over all ranges of relative amounts of these two germicides in the synergistic germicidal mixture.

I have also found quite unexpectedly that germicidal soap bars can be produced having synergistic germicidal properties and. yet being substantially as white as soap bars which do not contain any germicide therein, provided certain relative proportions of the two germicides are present in the synergistic germicidal mixture as further described below' The soap bars of the invention contain any watersolu-ble alkali metal soap. Typical of these are the watersoluble alkali metal, e.g., potassium and sodium, soaps of the saturated and unsaturated higher fatty acids having from about eight to about twenty-six carbon atoms, such as capric, caprylic, lauric, myristic, palmitic, stearic, oleic, linoleic, linolenic, arachidic, behenic, marigaric, tridechoic, and cerotic acids and the mixtures of such acids naturally occurring in fats, oils, waxes and rosins, such as the soaps of coconut oil fatty acids, tallow fatty acids, pig fat, fish oil fatty acids, beeswax, palm oil fatty acids, sesame oil fatty acids, peanut oil fatty acids, olive oil fatty acids, palm kernel oil fatty acids, cottonseed oil fatty acids, soyabean oil fatty acids, corn oil fatty acids, babassu oil fatty acids, rosin acids, abietic acid and. greases.

The soap bars also contain a synergistic germicidal mixture of 3,4,5 tribromosalicylanilide and 3.4.4-trichlorocarbanilide. The total amount of the synergistic germicidal mixture is generally from about 0.1% to about 0.5%, and preferably from about 0.3% to about 0.5%, by weight of the soap. However, if desired, lesser total amounts of the two germicides can be employed, although this would cause a decrease in the germicidal activity of the soap bar. Larger total amounts of the two germicides can also be employed, for example 2% by weight of the soap, if desired. Such larger total amounts are usually not used because they increase the cost of the soap bars as well as possibly causing skin irritation.

As noted above, the two germicides in the synergistic germicidal mixture can be present therein in any relative amounts, since all relative proportions have shown synergistic germicidal activity. In accordance with the preferred embodiment of the invention, however, the synergistic germicidal mixture is made up of from about 40% to about 10% by weight of the mixture of 3.4',5- tribromosalicylanilide and from about 60% to about 90% respectively by weight of the mixture of 3,4,4'-t-richlorocarbanilide. The use of such relative proportions results in the formation of soap bars which not only show synergistic germicidal activity, but also which are substantially as white as the same soap bars without the synergistic germicidal mixture therein. The most desirable relative proportions of these two germicides in order to produce synergistic germicidal activity as well as substantially white soap bars are from about 35% to about 20% by weight of the mixture of 3,4,S-tribromosalicylanilide and from about 65% to about respectively by Weight of the mixture of 3,4,4-trichlorocarbanilide.

If desired, the soap bar may also contain compatible adjuvants which do not materially interfere with the synergistic germicidal activity of the bars. Typical of such compatible adjuvants are perfumes and various fillers.

The soap bars are prepared in the conventional manner. For example, soap chips are weighed into -a mixer and the compatible adjuvants, if any, added thereto and mixed therewith for a long enough period to insure uniform mixing. The two germicides are then added to the mixer and the mixing continued to insure uniformity of the mix. The final mix can then be formed into frame or milled soap bars in accordance with the general procedure of the soapmaking art.

The germicidal effectiveness of the soap bars of the invention was determined by a standardized test, namely the Finger Imprint Test. This test measures the inhibitory effect of an 8% solution (basis soap weight) of the germicidal soap bar being tested.

For use in the test, cultures of Micrococcus pyogenes var. aureus are maintained on nutrient broth with transfers made daily. In preparing the agar plates, 0.1 milliliter of a 24 hour nutrient broth culture of the test organism is mixed thoroughly into 15 milliliters of melted nutrient agar, which is then poured into a Petri plate and permitted to harden. The fingers of the subject's hand are immersed in small beakers containing 8% solutions of the germicidal soap bar in question. The fingers are thoroughly rinsed with water, dried and then placed lightly for thirty seconds on the agar plate. The plates are incubated overnight, and the contacted areas examined for absence of bacterial growth. A sharply outlined clear zone is given a rating of 4, a clear area with a hazy periphery is rated 3, a hazy but perceptible imprint 2, a barely perceptible imprint l, and no detectable imprint 0. Intermediate ratings are designated by decimal units. Thus, the lower the numerical rating, the less effective the bactericide.

The invention will be further illustrated by the following comparative examples.

Germicidal soap bars were prepared containing various amounts of the synergistic germicidal mixture and various relative amounts of the two germicidal components thereof as shown by the data in the two tables set forth below. The soap component in these bars was a mixture of 80% Table I Example No. Percent TBS Percent TCC Finger Imprint Rating When Example 213 containing the synergistic germicidal mixture is compared with Examples 2 and 2A containing either germicidal component alone in the same amounts as present in the germicidal mixture, synergism is amply shown. Thus the finger imprint rating of Example 2B was 2.1 whereas the expected finger imprint rating for Example 2B was the total finger imprint rating of Example 2 plus Example 2A, namely 1.6 plus 0.1 or a total of 1.7. While Example 2B had synergistic germicidal activity, it was cream colored and would not be acceptable to those consumers who consider discoloration of soap bars to be objectionable.

When Example 3B is compared with Examples 3 and 3A, synergistic germicidal activity of an extremely high nature is shown. Thus Example 3B had a finger imprint rating of 1.9, whereas the expected finger imprint rating thereof was the total rating of Examples 3 and 3A, namely 0.2 plus 0.1 or a total of 0.3. Example 3B is representative of the preferred embodiment of the invention and was a soap bar which was substantially as white as the same soap bar without the synergistic germicidal mixture therein.

The synergistic germicidal activity of the soap bars of the invention is further demonstrated by the comparative data set forth in Table II below wherein the total of the synergistic mixture was 0.5% by weight of the soap.

When Example 6B of the invention is compared with Examples 6 and 6A, and also when Example 7B of the invention is compared with Examples 7 and 7A, the synergistic germicidal activity of the soap bars is clearly shown. The bars of Examples 63 and 7B were cream colored.

A comparison of Example 8B with Examples 8 and 8A and a comparison of Example 9B with Examples 9 and 9A show extremely high synergistic germicidal activities of these two preferred embodiments of the invention. Thus, the soap bar of Example 8B had a finger imprint rating of 3.3, whereas the expected finger imprint rating was the total finger imprint rating of Examples 8 and 8A, namely 0.2 plus 0.4 or a total of 0.6. The preferred embodiments of the invention illustrated by Examples 8B and 9B were soap bars which were substantially as white as the same soap bars without the synergistic mixture therein.

It will be appreciated that various modifications and changes may be made in the invention without departing from the spirit thereof, and accordingly the invention is to be limited only by the scope of the appended claims.

While the invention has been described in terms of soap bars, which are the preferred embodiment, it is equally applicable to soap powders, flakes, and liquids in which excellent germicidal activity without discoloration is desired. If such products are designed to be used at greater dilutions than those at which soap bars are normally used, the percentage of the germicidal mixture of the invention can be proportionately increased.

I claim:

1. A germicidal soap composition consisting essentially of a water-soluble alkali metal soap having from about 8 to about 26 carbon atoms and from about 0.1% to about 0.5% by weight of the soap of a synergistic germicidal mixture of from about 40% to about 10% by weight of the mixture of 3,4,S-tribromosalicylanilide and from about 60% to about 90% respectively by weight of 3,4,4'-trichlorocarbanilide; said composition being substantially as white as the same composition without said synergistic mixture therein.

2. A germicidal soap bar consisting essentially of a water-soluble alkali metal soap having from about 8 to about 26 carbon atoms and from about 0.1% to about 0.5 by weight of the soap of a synergistic germicidal mixture of from about 40% to about 10% by weight of said mixture of 3,4,5-tribromosalicylanilide and from about 60% to about 90% respectively by weight of said mixture of 3,4,4-trichlorocarbanilide; said soap bar being substantially as white as the same soap bar without said synergistic mixture therein.

3. A germicidal soap bar consisting essentially of a water-soluble alkali metal soap having from about 8 to about 26 carbon atoms and from about 0.1% to about 0.5% by weight of the soap of a synergistic germicidal mixture of from about 35% to about 20% by weight of said mixture of 3,4,S-tribromosalicylanilide and from about 65 to about respectively by weight of said mixture of 3,4,4-trichlorocarbanilide; said soap bar being substantially as white as the same soap bar without said synergistic mixture therein.

4. A germicidal soap bar consisting essentially of a water-soluble alkali metal soap having from about 8 to about 26 carbon atoms and from about 0.3% to about 0.5 by weight of the soap of a synergistic germicidal mixture of from about 35% to about 20% by weight of said mixture of 3,4,S-tribromosalicylanilide and from about 65% to about 80% respectively by weight of said mixture of 3,4,4-trichlorocarbanilide; said soap bar being substantially as white as the same soap bar without said synergistic mixture therein.

References Cited by the Examiner UNITED STATES PATENTS 3,057,920 10/1962 Schramm 252106 X 3,064,048 11/1962 Schramm 252-106 X FOREIGN PATENTS 106,388 2/1957 Argentina.

SAMUEL H. BLECH, Primary Examiner. ALBERT T. MEYERS, Examiner.

LEON D. ROSDOL, Assistant Examiner. 

1. A GERMICIDAL SOAP COMPOSITION CONSISTING ESSENTIALLY OF A WATER-SOLUBLE ALKALI METAL SOAP HAVING FROM ABOUT 8 TO ABOUT 26 CARBON ATOMS AND FROM ABOUT 0.1% TO ABOUT 0.5% BY WEIGHT OF THE SOAP OF A SYNERGISTIC GERMICIDAL MIXTURE OF FROM ABOUT 40% TO ABOUT 10% BY WEIGHT OF THE MIXTURE OF 3,4'',5-TRIBROMOSALICYLANILIDE AND FROM ABOUT 60% TO ABOUT 99% RESPECTIVELY BY WEIGHT OF 3,4,4''-TRICHLOROCARBANILIDEM; SAID COMPOSITION BEING SUBSTANTIALLY AS WHITE AS THE SAME COMPOSITION WITHOUT SAID SYNERGISTIC MIXTURE THEREIN. 